A Dissertation Submitted in Partial Fulfillment of the Requirements for Award of the Degree of Master of Business Administration in Corporate Management (MBA-CM) of Mzumbe University.This study examined the contribution of social security merger on improving the performance of the Public Service Social Security Funds (PSSSF). Lack of the insights whether the undertaken merger improves the performance of the PSSSF or not paves the way for this study to be conducted so as to bring into existence such insights. The PSSSF constitutes, among others, members’ contributions, funds transferred from former Funds, funds transferred from the NSSF by members transferred to the Fund, assets from the former Funds and monies from investments made by the Fund; the fund was specifically studied so as to examine the effects of the process of merger on the performance of the PSSSF in Tanzania, to find out the extent to which PSSSF monopoly influences scheme benefits and to find out the challenges that PSSSF encounters This study had been the case that attracted in-depth investigation of a particular situation so as to attain in-depth knowledge about the research problem (the contribution of social security merger on improving the performance of the PSSSF). Based on such case study, both stratified and simple random sampling procedures were applied to obtain a sample size of 10 managerial staff and 30 non-managerial staff. The conceptual framework with both independent and dependent variables was used to enlighten this study. To collect the required data, questionnaire and in-depth interview methods were applied and then, the collected data were analyzed quantitatively and qualitatively. The results of the analysis from the revealed findings show the contribution of the merger on the operating performance of Public Service Social Security are an expansion of the fund coverage to cover all public service employees in Tanzania, a large number of workforces that work to secure objectives of the PSSSF, enhancement of competitiveness of the fund which goes together removal of unnecessary competition so as to increase the market power of the fund with the ability to pay members’ benefits The study concluded that merger improves the operating performance of the fund regardless of the post-merger challenges. Then, the study recommended the